Le 13/12/2012 07:56, Lester Anderson a écrit :
Hi Serge
A quick question. In the context of the equation, what is the purpose
of the ones(t) part? The help states that this creates a matrix
composed of ones.
(B./(m1.^3*%pi).*sin(m1*%pi/B)) is a column vector, the multiplication by
ones(t) which is a row vector is a way to create a matrix with identical
columns
. Ina similar mannerm1.^2*t
creates a matrix multiplying the column vectorm1.^2 by the row vector t
g=c*sum((B./(m1.^3*%pi).*sin(m1*%pi/B))*ones(t).*exp(-(m1.^2*t/tau)),1);
Probabaly a very simple answer.
Cheers
Lester
On 12 December 2012 22:46, Lester Anderson <[email protected]
<mailto:[email protected]>> wrote:
Many thanks Serge :) That worked great!
Helps to see how the syntax should work.
Cheers
Lester
On 12 December 2012 22:29, Serge Steer <[email protected]
<mailto:[email protected]>> wrote:
I think the following code fullfil your wish...
n = 0:1:20 ;// series in the expansion
B = 1.5; //beta factor
Tm = 1300*274.15; //base-lithosphere temperature [C]
tau = 62.8; //lithosphere cooling thermal decay constant [Ma]
a = 125000; //equilibrium lithospheric thickness [m]
alpha = 3.28e-5 ;//thermal expansion coefficient K^-1
// Tm needs to be converted to Kelvin - multiply by 274.15
rho = 3300;
t = 0:5:150; //lithosphere age [Ma]
G = 6.67e-11;
// LTGA with increasing age of oceanic lithosphere
c=8*G*alpha*rho*a*Tm/%pi;
m=(0:20)';m1=2*m+1;
g=c*sum((B./(m1.^3*%pi).*sin(m1*%pi/B))*ones(t).*exp(-(m1.^2*t/tau)),1);
clf;plot(t,g)
Serge Steer
------------------------------------------------------------------------
*De: *"Lester Anderson" <[email protected]
<mailto:[email protected]>>
*À: *"International users mailing list for Scilab."
<[email protected] <mailto:[email protected]>>
*Envoyé: *Mardi 11 Décembre 2012 08:16:01
*Objet: *[Scilab-users] Summation query in Scilab
Hello,
I have an equation structured like in the attached,
however I am unsure of the correct syntax to compute in
Scilab.
One can calculate the first term of the expansion but
obvioulsy it needs to go to a large number (approximating
infinity eg 20).
I am sure this is something very straightforward!
Any ideas welcome.
Thanks for the help
Lester
att: image of equation, test code
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